Assessing the sorption of uranium and thorium from simulated solutions using chemically treated biomass of Sargassum aquifolium macroalgae

Abstract

This study aimed to investigate the potential application of activated Sargassum aquifolium macroalgae (ASAM) as a biosorbent for uranium(VI) and thorium(IV) ions, employing controlled experimental conditions. The parameters examined included pH, biosorbent mass, initial concentration, contact time, and temperature. To enhance sorption characteristics, the raw Sargassum aquifolium macroalgae (SAM) biomass underwent separate pre-treatments using phosphoric acid (H3PO4) and potassium hydroxide (KOH). Various models were employed to analyze the kinetic and sorption isotherm data, and thermodynamic parameters were determined to assess the sorption mechanism. The KOH-treated SAM demonstrated a higher capacity for biosorbing U(VI) and Th(IV) compared to the acid-treated biomass. The sorption mechanism was investigated through characterization techniques such as FTIR, SEM/EDS, XRD, Zeta-potential, and BET analysis. The desorption-sorption cycle efficiency of both sorbents was evaluated, indicating that 0.1 mol L-1 HNO3 exhibited the most efficient desorption reagent for both metal cations over five consecutive cycles. These findings suggest the potential of ASAM as a biosorbent for removing U(VI) and Th(IV) from aqueous solutions. Furthermore, the study demonstrated the remarkable effectiveness of the two activated sorbents in eliminating U(VI) and Th(IV) ions from real wastewater samples.